0005剑指offer替换空格python&golang实现 Marathon

请实现一个函数，把字符串 s 中的每个空格替换成"%20"。

示例 1：

输入：s = "We are happy."
输出："We%20are%20happy."

限制：

0 <= s 的长度 <= 10000

来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/ti-huan-kong-ge-lcof

python

# 剑指005-替换空格
class Solution:
    def replaceSpace1(self, s: str) -> str:
        """
        遍历字符串，时间O(n), 空间O(n)
        :param s:
        :return:
        """
        res = []
        for i in range(len(s)):
            if s[i] == ' ':
                res.append("%20")
            else:
                res.append(s[i])
        return ''.join(res)

    def replaceSpace2(self, s: str) -> str:
        """
        扩充字符串+双指针
        :param s:
        :return:
        """
        cnt = 0
        for i in s:
            if i == ' ':
                cnt += 1
        res = [""] * (len(s) + 2*cnt)
        i = len(s) - 1
        j = len(s) + 2*cnt - 1
        while i >= 0:
            if s[i] != ' ':
                res[j] = s[i]
                j -= 1
            else:
                res[j-2] = '%'
                res[j-1] = '2'
                res[j] = '0'
                j -= 3
            i -= 1
        return ''.join(res)


if __name__ == "__main__":
    s = "sky is blue "
    test = Solution()
    print(test.replaceSpace1(s))
    print(test.replaceSpace2(s))

golang

package main

import (
	"fmt"
	"strings"
)

func main() {
	s := "blue is my skay"
	fmt.Println(replaceSpace1(s))
}

// 遍历字符串
func replaceSpace1(s string) string {
	res := []string{}
	for i := 0; i < len(s); i++ {
		if string(s[i]) == " " {
			res = append(res, "%20")
		} else {
			res = append(res, string(s[i]))
		}
	}
	return strings.Join(res, "")
}